Dual firing rate oil burner of the pressure atomizing type



Dec. 13, 1949 T. c. o'DoNNELL ErAL $91,201

DUAL FIRING RATE OIL' BURNER 0F THE PRESSURE ATOMIZING TYPE Filed Aug.12. 1948 5 Sheets-Sheet l T v ATTOR EYS Dec., H3, 1949 T. c. 'DONNELLrAL 2,491,201

DUAL FIRING RATE OIL BURNER OF THE PRESSURE ATOMIZING TYPE 5Sheets-Sheet 2 Filed Aug. l2. 1948 5 L uw T ML E NdA. M v WTHO man." dwA @.mmw.

Dec. 13, R949 r. c. ODNNELL ETAL 2,491,201

DUAL FIRING RATE OIL BURNER 0F THE PRESSURE ATOMIZING TYPE 5Sheets-Shee't 3 Filed Aug. 12. 1948 A La.- w 1| l *m' N ffl/IIA w milDec. 13, 1949 T. c. o'DoNNELl. Er AL 2,491,201

' DUAL FIRING RATE OIL BURNER 0F THE PRESSURE ATOMIZING TYPE 5Sheets-Sheet 4 Filed Aug` 12. 1948 Chiu@ f 22ml ATTORNEYS Dec. 13, 1949T. c. 'DONNELL ErAL 2,491,201

DUAL FIRING RATE OIL BURNER 0F THE vPRESSURE ATOMIZING TYPE 5Sheets-Sheet 5 Filed Aug. 12. 1948 N L 5 www T @man V9 H WOW dw N NN Enmm T.

menudo. 1a, 1949 DUAL FIRING .RATE DIL PRESSURE ATOMIZING BURNER oF 'mitma Terrence C. ODonnell, West Springfield, and- Joseph A. Logan, Gilbert&

Hadley, Mass., Barker Manufacturing Company,

orsto West Springfield, Mass., a corporation of MassachusettsApplication August 12, 1

1 'rmsmvennon relates to en improved cual-nring-rate oil burner,.adapted for house heating service and of the type in which the tworates of now of atomizedoil are produced from a single pressureatomizing nozzle by varying the pressure of the oil fed to such nozzle.

The invention has for an object the provision in a pressure-atomizingburner of the general type disclosed in the Logan Patent No. 2,411,048,dated November 12, 1946, having within the burner structure a combustionchamber in which the greater part of the combustion occurs, ofquickacting means for changing' the atomizing pressure to change thering rate from a relatively low firing rate, lower than could be usedwith the same nozzle in an ordinary gun type burner, to a relativelyhigh iiring rate, higher than would ordinarily be used with the samenozzle in the ordinary gun type burner, characterized in that an amplespread between the high and low ring rates can be hadvwith a smallerspread in atomizing pressures than could be had in an ordinary gun typeburner; in that the maximum atomizing pressure is kept well within thelimits of the capacity of the oil pumps usually used in g-un type oilburners, and in that a wide spread in ring rates may be had because theburner operation will not be limited by the size of the rebox in theheating apparatus since the combustion chamber is provided within theburner structure.

Assuming that the new burner is to be used for house heatingand that adifferential of one half gallon per hour between the two ring rates isdesired, and that the atomizing nozzle of the burner is, for example,one rated to give an oil burning rate of one gallon an hour at anatomizing pressure of about one hundred pounds per square inch, the waythe burner of this invention operates is: the low iiring rate isobtained by lowering the atomizing pressure enough below the ratedpressure of the nozzle to get an oil-burning rate of approximately .7 ofa gallon per hour and the high rate is obtained by raising theatomizin'g pressure enough above the rated pressure of the nozzle to getan oil burning rate of approximately 1.2 gallon per hour. The differencebetween the rates is then a half a gallon an hour. Other things need tooperate in the burner in relation to this dual rate operation. The oilrateneeds to be changed from one to another, 'as a. diierence A berhaving a peripheral 94s, serial No. 43.326

s claims. Y (ci. 15s-.28) A .in the need for heatnoccurs. Asvsuch oilrate is' changed, the air rate needs to be changed to give an eicientair-oil ratio for burning and the way 'of changing the oil atomizingpressure to change the oil firing rate needs to be considered withrelation to economy, simplicity, and the coordination of its action'withthe action of the change in air rate all of which changes are preferablyautomatically controlled by thermostat action. One advantage aimed at isto provide a mode of operation which takes into account the desirabilityof making as few changes in construction of routine and available oilburner elements as will get the result in an inexpensive manner andutilize the mass-produced parts in the oil burner industry.

The invention will be disclosed with reference to the accompanyingdrawings, in which Fig. 1 is a side elevational view of an oil burnerembodying the invention;

Fig; 2 is a front elevational view of the burner with parts broken awayto show the air control shutter of the fan together with the-manual ad'justing means and the automatic actuating meansfor the shutter;

Fig. 3 is a sectional elevational view taken on the line 3-3 of Fig. 2;

Fig. 4 is a cross sectional view taken on the line 4 4 of Fig. 3;

Fig. 5 is a diagrammatical view of the oil supply system of the burner;

Fig. 6 is a sectional 5-6 of Fig. 3;

Fig. 7 is a wiring diagram of the electrical controls for the burner;

planview taken on the line Fig. 8 is a fragmentary sectionalelevationalv view showing a' diierent form vof combustion chamber; and

Fig. 9 is a cross sectional view taken on the line 9--9 of Fig. 8.

Referring to these drawings, the burner includes within its structure acombustion chamber I (Fig. 3). This is formed by a tubular memwall 2which is cylindrical, an inner end wall 3, which as shown is offrusta-,conical form, 'and an open outer end 4. In the peripheral wall 2of the combustion chamber, there are a plurality of air inlet openings,which may as shown consist of a circular series of slots i, each openinginto the chamber, as shown in Fig.

4, substantially tangentially to the inner surface .est

o! wall 2. These slots provide for the admission of air in whirlingstream extending from one end to the other of the chamber I. There mayalso be a circular series 'oi similar air inlet openings 5 in thepart-conical portion of the inner end wall 3. `Supported centrally fromthe inner end wall 3 (Fig. 3) is a tubular support 1, bearing on itsouter end a nozzle 3, which is of the oil-pressure-atomizing type and isadapted to be connected at its inner end to a supply of oil underpressure. This nozzle is located near the inner end and coaxially of thecombustion chamber and is adapted to emit a spray of atomized oilgenerally forwardly of the combustion chamber toward the open outlet end4 thereof. A pair of ignition electrodes 3 (Fig. 4) also extend throughand are insulated from the inner wall 3 with their inner ends properlylocated to ignite the spray emitted from nozzle 8.

The combustion-chamber-forming member described is telescoped into theouter end of an air supply tube I0, herein shown as cylindrical in form.The imperforate peripheral wall of tube I Ii is radially spaced from theperipheral wall 2, forming between them an air jacket II, whichsurrounds the entire combustion chamber I and with which the airadmission openings 5 and 3 communicate. The outer end of tube Ill is inturned to engage the peripheral wall 2 near its outer end and therebyclose the outer end of the air Jacket' lI. The inner end of tube I0 isconnected to receive air from a suitable fan.

The air supply fan is shown at I2 (Figs. 2 and 3) and it is mounted in ahousing I3, formed in a casting I4, suitably supported, as from theiloor by a pedestal I5. In the lower part of casting I4 is a cylindricalpassage I6 (Fig. 3) into the rear end of which fan I2 discharges. To theforward end of passage I6, the inner end of tube. I0 is secured, asindicated. The rear end of passage I6 is normally closed, as by a coverI1, secured by screws I8 (Fig. 6) so as to be easily removable to gainaccess to the interior of passage I6, when required. The air inlet tofan I2 is a circular Opening I9 (Fig. 2) formed in one end wall of itshousing I3. Connected with and extending outwardly from this end wallare two laterally-spaced side bars 20, one of which is shown in full inFig. 2 and both of which are indicated by dotted lines in Fig. 1. Thesebars 23 at their outer ends are connected with and support a circularilange 2|. An air inlet control shutter 22 (Fig. 2) is movable towardand away from opening I9to vary the effective area of the air inlet tofan I2. This shutter has a screw thread engagement with a screw 23,which has near each end a smooth cylindrical portion. These cylindricalportions are slidably, -as well as rotatably, mounted one in a bearing23', formed in the end wall having the fan inlet I3, and the other in abearing 24, formed in the flange 2I. On screw 23 is a shoulder 25adapted to abut the adjacent end face of bearing 23 and limit the inneraxial sliding movement of the screw 23 and thereby determine theposition of the shutter for low ring rate operation. Such position isvariable and may be adjusted by rotating screw 23 and thus moving theshutter 22 toward or away from the air inlet opening I3. A rod 23, ilxedat one end to ilange 2I, extends in parallel 'and underlying relation.with screw 23, is slidably engaged with shutter 22, and serves toprevent the latter from rotating when the screw is turned. A screw 21 isthreaded into dangle 2I adjacent screw 23 and is adapted to be engagedby a circumferentially grooved collar 2l,

4 tlxed on screw 23, for the purpose of limiting the axially outwardmovement of screw 23. The collar, when engaged with screw 21, determinesthe high tiring rate position of shutter-22. Buch position is variableand may be adjusted by turning screw 21.

The shutter may be automatically bel tween its high and low nring ratepositions by means of a lever 23, the upper end of which is engaged inthe groove of collar 23. This lever is received near its lower end in avertical slot 33 in a block 3I, which is secured by screws 32 to oneside wall of the casting I4. 'I'he lever 23 is fulcrumed on a pin 33ilxed in said block. Also formed in this block is a cylinder 34,containing a piston 35, the rod 35 of which is pivotally connected atits outer end to the lower end of the lever 23. The outer end ofcylinder 34 is closed by an annular plug 31 which slidably engages rod35. Between this plug and the piston is a spring 38, which tends toforce the piston inwardly in its cylinder and thereby yieldingly holdthe shutter 22 in the`high firing rate position illustrated. When oilunder pressure is admitted to the inner end of cylinder 34, by means tobe described, the piston will be moved outwardly, actuating lever 29 tomove the shutter 22 into its low ring rate position.

The fan I2 has its hub 33 xed to the shaft 40 of an electric motor 4I,which is secured to that end wall of the fan housing which lies oppositethe air inlet I3. This motor also drives the pump'for supplying oil tonozzle 8. This pump, in the present case, is combined with a illter andpressure regulating valve, these elements being respectively located inthe casingparts 42, 43 and 44 (Fig. 1). These casing parts are allconnected to and supported by a hub 45 (Fig. 2) which lits into a holein flange 2| and is suitably fixed therein as indicated. 'Ihe driveshaft 46 of the pump passes through hub 45 and is ilxed to the drivenelement 41 of a centrifugal clutch, the driving element 43 of which isconnected by a ilexible coupling 43 to the hub 33 of fan I2. The shutter22 has a central opening to freely receive the clutch element 41. Thisclutch may be like that of U. S. Logan Patent No. 1,985,934, datedJanuary 1, 1935, and is used for the purposes fully set forth therein.'I'he arrangement provides for starting the pump after the fan, and onlyafterrthe latter has attained high speed, and for stopping the pumpbefore the fan, and while the latter is still revolving at high speed.

The oil supply system in its entirety is shown in Fig. 5 together withthe means by which the ring rate of nomle 3 may be changed by varyingthe pressure at which the ou is fed to the nozzle 3. 'I'he pump in thiscase consists of a pair of intermeshing gears 55, both of which arehoused in the casing part 42 and one ot which is xed on the describedshaft 45. The intake of the pump is connected by a diagonal passage 5Ito a chamber 52, formed in the upper part of the hollow casing part 43.In the lower part of the latter is a filter chamber 53, containingillters 54. The lower end of chamber 53 is connected to a pipe 55,adapted to connect with an oil supply tank (not shown). Oil is drawn upthrough pipe into chamber 53, passes through the nlters 54 and thenceinto chamber 52, from which it ows by passage 5I to the pump. The latterforces oil outwardly through a passage 55 into a lower chamber 51 formedin the hollow casing part 44. In chamber 51 is a cut-oi valve 53,mounted on the lower end of a cylindrical member 53, which is ilxed toand depends from interior of member 8| above the seat valve 58. Theupper and flanged end of belas'emi 6 l on from-chamber u t6 manche spacemund the lower and closed end of a bellows 88. The member I8 is slidablein a tubular member 8|, which upstands from the base of chamber 81.Radial holes 82 in member 8| below member 58, enable oil to ilow from camber 51 into the of cut-oi! lows 80 is held against an annular shoulder58 by a spring 84, acting between the cover 55 and a washer 88, bearingon the flange of the beilows. Within the bellows and acting betweentheclosed end thereof and a spring seat 81, which is adjustable by ascrew 88 in'cover 55, is a spring 88. -When the pressure of the pumpedoil reaches a predetermined value, say for example 45 pounds per squareinch. the bellows 80 will rise upwardly enough to allow oil to i'iow outof chamber 51 through radial holes into the outlet passage 1 0, which isconnected by a pipe 1| to the nozzle support 1 and thus to nozzle 8.

The bellows 50 also controls a by-pass valve consisting of thecylindrical member 58, the tubular member 8| and a recess 12 in one sideof member 58. This recess 12 is initially covered by the inner wall ofmember 8| as shown. However, when the pressure o i the pumped oilreaches another and higher predetermined pressure, say for example 50pounds per square inch. the bellows 80 will have risen far enough tolift the recess 12 above the upper end of member 5|. Then some of theoil in chamber 51 will enter recess 12 and pass by way of a connectingpassage 18 in member 58 into the interior of bellows 60 and thence intoan upper chamber 14 formed in casing part 44. Oil iiows from chamber 14through a passage 15 into a by-pass chamber 16 formed in a casing part11 located between the parts 48 and 44. The by-pass chamber 16 isconnected by a pipe 18 to the inlet of a two-way valve 18. This valve,shown diagrammatically in Fig. 5, has a liquid-receiving chamber, whichis formed within a tube 80 of non-magnetic material and which is closedat opposite ends except for outlet passages 8| and 82. A valve 88, ofmagnetic material and located inside tube 80, is held by a spring 84-against one end seat to close the outlet 82. A

solenoid 85 encompasses tube 80 and is operable, when energized, to movevalve 88 against spring 84 into engagement with its other seat to closethe outlet 8| and at the same time open outlet 82. I'he latter isconnected by a pipe 88 to suction pipe 55. Thus, when the solenoid 85 iseuergized, by means to be later'described, the liquid flowing past theby-pass valve 12 may flow,

without restriction, by way of pipe 18, tube 80,

passage 82, and pipes 85 and 55 back to the suction side of the pump.The by-pass valve 12 will -then determine the maximum pressure of theoil that is supplied to nome 8 and the cut-off valve 58 will determinethe minimum pressure. The f maximum pressure, thus determined is for thelow firing rate of the burner.

' To secure the relatively high rate of flow of oil vto nozzle 8, asecond by-pass valve 81 is provided in a chamber 88 formed in a casing88. The described outlet 8| of valve 18 is connected by a pipe 80 tochamber 88. Valve 81 is mounted on the lower end of a cylindrical member8|, fixed to and depending from the lower and closed end of a bellows82, which is held in place in casing 88 in the same way as the bellows80 and which is forced downwardly by an adjustable spring 88 to hold thevalve 81 toits seat. Member 8| is vertically slidable in a tube 84,which has radial openings 85 above the seat of valve 81 to allow 88,which is connected by a controls an outletpassage pipe 81 to lsuction toopen at a much valve 81. This valve pipe 55. Valve 81 is adjusted higherpressure than the first bil-Dass valvl1 say us' for example 150 poundsper square inch.` when the solenoid valve 88 is positioned as shown, thesecond by-pass mum pressure of oil fed to nozzle to secure the highrateof ilow. l

As the rate of now of oil fromnozzle 8 is varied, the rate of flow ofthe air for combustion must be spring 88, acting through lever 28, tendsto hold the air shutter 22 in position for the higher rate of air flow.The piston 85 is moved by oil pressure into position for the lower rateof air flow. This is accomplishedunder the control of a second solenoidvalve 88, similar to valve 18. The solenoid 88 moves a valve |00 ofmagnetic material, located within a non-magnetic tube |0I. away from oneend seat and into engagement with the other. A spring |02 normally holdsvalve |00 in the illustrated position, in which it closes an vinletpassage |08, which is connected by a pipe |04 to the nozzle supply pipe1|. The

move valve |00 to closeY inlet |03 and open the passage |06, which isconnected by a pipe |01 to suction pipe 55. Thus, oil will be drawn outof cylinder 84 to enable piston 85 to be moved back by spring 88 intoits illustrated position.

The combined pump', filter, cut-oft' valve and first by-pass valve areshown in Fig. 5 reversely from Fig. l, as if taken on'the line 5-5 ofFig. 2.

Fig. 5 is to a considerable extent diagrammatical and does not show allthe parts in their actual locations. Fig. l, however, locates all theparts,

including the pipe connections, as they actually are in the burner. Thevalve casing 88 is secured by screws |08 to the wall of air passage nearthe rear end thereof. The solenoid valves 18 and 88 are mounted in theblock 3| below the cylinder 84. These vvalves are standard articlesavailable in themarket and they are shown only diagrammatically hereinbut this will suillce for an understanding of their functions. The oilpipe 1| extends through a recess in the cover i1 into the rear end ofthe air passage 46 and thence forwardly in the latter and tube |0 (Fig.3) to connect with the rear end of the tubular support 1 for nozzle 8.

Referring now to some of the details of the exemplary burner, thecombustion chamber l (Fig. 6) is supported at its forward and outlet end4 by having its peripheral wall 2 rest on the nturned annular flange |08of air tube |0. Suitably fixed in hubs formed on the rear side of innerend wall 8 are two laterally-spaced rods H0, which extend rearwardly inair passage I6 and terminate spark electrodes 8 are mounted ininsulators ||8,

valve 81 will control the maxiproportionately varied. As described, the

7 which in turn are adiustably secured in the support ||2. The ignitiontransformer ||4, indicated in part in Fig. 6. is suitably xed to anouter wall of passage I8 with its high tension terminals I| extendinginto such passage-(see also Fig. 3) and being connected by wires I I9 tothe electrodes 9. When the cover |1 is removed. the ends III of rods I|0may be drawn toward each other out of their respective holes and thenthe rods may be pulled rearwardly in the air passage Il carrying withthem the combustion chamber with nozzle 9 and electrodes 9in assembledrelation thereon for inspection, adjustment or repair. The air shutter22 sheet metal cover I I1 engaging at one end with the periphery of ange2| and at the other end with the periphery of a flange I I9 on fanhousing I3 and is suitably secured to such flanges (Fig. 1). The cover Il1 has a plurality of air inlet openings ||9 therethrough.

A typical form of control system for a househeating oil burner is showndiagrammatically in Fig. 7. A room thermostat switch |20 is connected inseries with the secondary |2| of a step-down transformer and the coil|22 of a relay by means of Wires |23, |24 and |25. The primary |26 ofthis transformer is respectively connected by wires |21 and |29 to thesupply wires |29 and |30, which lead from a suitable source ofelectricity, such as a 115 volt A. C. circuit. The relay coil |22 isadapted when energized to close a switch |3|, one terminal of which isconnected by a wire |32 to supply wire |29 and the other terminal ofwhich is connected by wires |33 and |34 to one terminal of motor 4|. Theother terminal of the latter is connected by a wire |35 to the othersupply wire |30. The primary |36 of ignition transformer |I4 isconnected by wires |'31 and |39 to Wires |34 and |35, respectively. Thesecondary |39 of transformer ||4 is connected by the described wires IIBto electrodes 9. When switch |3 closes on a call for heat, it starts theburner` motor 4I and energizes the ignition transformer ||4 to producesparks between the electrodes 9. Such is a simplilied and conventionalillustration of the usual control for a house-heating burner. Thediagram omits the various safety devices, which are usually used inconjunction with such a burner to stop it on failure of combustion andin the event of various other emergencies. It is understood that any orall such usual safety devices may be used in the present control systembut, since these devices are old and 4well known, they have been omittedto avoid needless complications in the disclosure.

The solenoids 95 and 99 may be controlled in connection with such acontrol system in the following manner.- These solenoids are connectedin parallel to wires |40 and I'4I. Wire |40 connects with one terminalof a tiring-rate control switch |42, the other terminal of which isconnected by a wire |43 to wire |33. The wire |4I is connected to supplywire |30. Whenever, the switch |42 is closed, the solenoids 95 and 99will be connected so as to be energized when th'e switch |3| closes tostart the motor 4| and the solenoid valves 93 and` |00 will then beoperated to provide for the lower oil pressure and smaller air inletopening required for operation at the low firing rate. If switch |42 isopen, the solenoids will not be energized, when the burner starts, andthe valves-93 and |09 will remain positioned as shown for the higher oilpres- (Fig. 2) and its adjusting means are usually enclosed by apart-cylindrical sure and larger air inlet opening needed for operationat the high firing rate. The switch |42 may be operated manually orautomatically as desired. It may be, and desirably is, a thermostatswitch, responsive to the temperature at some location, where thetemperature will be indicative of the need for low or high nring rateoperation. It may, for example, be responsive to outdoor temperature.

In Figs. 8 and 9. there is shown another form of combustion chamber.'I'his chamber, designated |45, like the chamber is formed within acylindrical .wall |43. having a frusto-conical inner wall |41 at one endand being open at the other end. As in the nrst described construction,most of the air for combustion is introduced through the peripheral wall49 around the spray of atomized oil emitted from the nozzle 9 but theair-admission openings, in this case, are radiallydirected and in theform of many small and closely-spaced perforations |49 distributed overthe entire area of wall |45. Similar air admission openings |49 areprovided in end wall |41. The nozzle 9, in this case, is located insidea tubular shield |50, fixed to the end wall |41 and having on its innerend an inturned frusta-conical iiange I5I with a central opening throughwhich the oil spray emitted from nozzle 8 enters the combustion chamberin a direction generally lengthwise thereof. The tube |50 is spaced fromthe nozzle support 1 leaving a passage for air to dow into thecombustion chamber, such air being deflected by flange |5|' inwardly tomeet the oil spray and entering with the latter through the centralopening. The ignition electrodes 9 extend through and are insulated fromthe end wall |41 and their inner ends are properly positioned to ignitethe combustible mixture. 'Ihe insulators |I3 for electrodes 9 aremounted in a support |52 ilxed to tube |50. This combustion chamber |45is telescoped into an air supply tube |53, as before, forming an annularair jacket |54 around the combustion chamber. This jacket communicatesat its inner end with the air passage |9 from fan I2 and at its outerend is closed by an annular ring |55, fixed to tube |53 and supportingthe outer end of the combustion chamber. The inner end of the latter maybe supported by a plurality of pins |59 (Fig. 9).

In the air jacket |54 is a baille, consisting of an annular ring |51having its'inner periphery slidably engaged with the outer periphery ofwall |49 and its outer periphery slidably engaged with the innerperiphery of tube |53. In this baille are a plurality of air openings|59. The position of this bafe in the air jacket may be adjusted bymeans of a screw |59, rotatably mounted at its outer end in a ring |55and at its inner end in a lug |60, fixed to tube |53. The screw has athreaded engagement with baille |51 to move the latter longitudinally ofjacket I 54, when the screw is turned, and this may be done by a knurledknob IGI, xed to the inner end of the screw and projecting through aslot in tube |53 so that it may be actuated from outside the leftter.'I'his baille enables the size of the :lets of air, .which issue throughsome of the perforations |43, to be varied with respect toilets of airwhich issue through other perforations |49. The perforations |49, whichare located to the right of baille |51. receive air only by way of thebame openings |59. the aggregate area of which is substantially lessthan that of Jacket |54. Because of the restriction of air flow bybaille |51,

einer I the air issuing from the perforations |40, whicharelocatedtotherightofthebafile,willbeats less rate and pressure thanthe air issuing from the perforations |48 which are located tothe leftof the baille The baile 181, if not needed in any particular case, canbe rendered inoperative by moving it to the front end of jacket |04until it abuts ring |00.

'I'he operation of the case the switch |42, is moved to the properposition for the tiring rate desired. As shown, this is doneautomatically by the thermostat element of the switch but obviously theswitch may be manually operated, if desired. Assuming that the switch|42 is open as shown, the burner will, when started, operate at the hightiring rate because neither the solenoid 85nor the solenoid 08 will beenergized, when the burner motor switch l3| closes on a demand for heat,evidenced by the closing of room thermostat switch |20. When switch |3|closes, the motor 4| starts. driving with it the fan l2 and, after themotor and fan have acquired considerable speed, the clutch 41, 48 willengage to drive the oil pump 80. Air flow through tube A before oil flowfrom the nomle 8. The air will be supplied at the high rate because theair shutter 22 will be held by spring 30 in the high rate position shownin Fig. 2. Also the cylinder 34 is connected, as shown in Fig. 5, bypipe |05, tube |0|, passage |08 and pipe |01 to the suction pipe 5,5 ofthe pump, thus supplementing the action of spring 38 in holding shutter22v in the high rate position. Oil will be supplied by the means shownin Fig. 5. The cut-oil valve 58 will open, when the minimum oil pressurehas been attained, and oil will flow through conduit 1| and support 1 tonozzle 8. As the pressure of the pumped oil increases, by-pass valve 12will open allowing some of the pumped oil to iiow by way of passage 13hollow .bellows 60, chamber 14, passage 15, chamber 18, pipe 18, tube00. passage 0| and pipe 80 into the chamber 08 of the second by-passvalve 01, which will not open until the maximum pressure needed for highnring rate operation has been established. The second by-pass valve thenopens to allow excess oil to pass through pipe 01 to pipe 55 and thus tothe suction side of the pump. The oil spray from nozzle 8 (Fig. 3) isemitted into the combustion chamber and there mixed with air, someentering through thc slots I in the inner end wall 3 of the combustionchamber but the larger part entering through the slots in the peripheralwall 2 of the chamber. The combustible mixture is ignited by a sparkproduced between the electrodes 8 and burns to a large extent within thelimits of the combustion chamber. The iiame does not extend very farbeyond the open outer end 4 ofthe chamber, say for a distance aboutequal to one `quarter of the length of the combustion chamber. Thisdistance that the flame extends from the open end of the chamber is soshort that it is unnecessary to build a combustion chamber in theheating apparatus, which is to be fired by the burner. as is necessaryin the case of the ordinary gun-type burner. It might be desirable toplace a refractory brick in front of the nozzle against the wall towardwhich Y the flame is directed. but nothing more would be required in theordinary installation. The burner will ordinarily continue to operate atthe high rate until the demand for heat is satisfied. when the motor 4|(Fig. '1) is 'stopped and the ignition invention will next be'described. The :tiring rate control device, in this lo and Jacket willbe started l0 switch |0|, caused by tne opening of the room thermostatswitch |28.

Assuming now that the switch |42 is set for low iiring rate operation.when the switcn |3| 5 closes on a demand ror heat irom tne burner,

the motor 4| will be started and tne igmtion transformer ||4 energizedas beiore, but in addition, botn solenoids an and sa will be energizedbecause switch |e2 is now closed. Thus, when the burner starts, thevalves 83 and Illu. will be vmoved by the solenoids 85 and 8s into theirextreme right hand positions. The outlets 8| and |08, which wereformerly open for the high ilring rate operation, will now be closed andthe 1'5 previously-closed passages 82 and |03 will be opened. Thecut-off valve 58 will open at the minimum pressure, as before, and allowflow of oil to nozzle 8 and, after the pressure increases slightly, thefirst by-pass valve 12- will open and allow some ofthe pumped oil toflow directly back toward the suction side of the pump. Such oil flowsby way of passage 13, bellows 60, chamber 14, passage 15, chamber 18 andpipe 18 into tube 80, -as before, but this oil now has to leave throughthe outlet 82, which is connected by pipe 85 to the suction pipe 55 ofthe pump. Oil is thus supplied to nozzle 8 at the low pressure for lowring rate operation. At the same time that oil iiows to nozzle 8, someoil is admitted through pipe |04 and passage |03 into the tube |0| andpasses out through pipe |05 to cylinder 34, forcing piston to the rightand causing air shutter 22 to be moved into its low rate position. Thecombustible mixture is ignited, as before, and op- 35 eration of theburner at the low ring rate ordinarily continues until the demand forheat is satisfied, when switch |3| opens to stop motor I, 4| anddeenergize the ignitiol'ii"y transformer ||4 and the solenoids 85 and89.

A change from one firing rate to another can occur while the burner isoperating. The firing rate control switch |42 can move from open toclosed position or vice versa, whenever desired, or whenever the demand,which inuences the 45 thermostat switch |42, changes. A change from onefiring rate to another can occur without any interruption in the flow ofoil to nozzle 8. Oil is supplied to the nozzle as soon as the cut-oi!valve 58 opens and, so long as the minimum preslo sure is maintained,this valve will remain open and allow oil to reach the nozzle. If theburner is operating at the low ring rate and a change to the high iiringrate is made, the valves 83 and |00, which were previously heldin theirright hand positions by the energized solenoids 85 and 89, are movedback by springs 84 and |02, respectively, into their illustratedpositions. Valve 83 now directs the oil, which is by-passed from the rstby-pass valve 12, into passage 8| and 6|) pipe 90 and thence into thechamber 88 of the .i second by-pass valve 81. The oil pressure will nowincrease until the high ring rate pressure is attained, when valve 81will open, as before described to maintain such pressure constant.

88 But the oil flow to the nozzle 8 is not cut-of! during the transitionfrom the low to the high firing rate. The oil supplied to nozzle 8gradually ini creases in pressure. The valve |00 will now connectcylinder 34 by way of pipe |05, tube |0|,

passage |08 and pipe |01 to the suction pipe 55 of the p p. The spring38 will now move air shutter 2 into its high rate position.

Assume now that a change from high iiring rate operation back to lowfiring rate operation is transformer I |4 is deenergized4 by the openingof 1l desired. The tiring rate control switch |42 will Ill close.causing the solenoids 85 and 98 to be energized, drawing valves I3 andl|00 into their extreme right hand positions. Valve 83 will then cut oiTthe flow of oil which is by-passed by valve I2 to the second by-passvalve 81 and direct such by-passed oil through outlet 82 and pipe 86directly into the suction pipe 55. The oil supplied to nozzle 8 willrapidly decrease in pressure until it reaches that for which the rstby-pass valve is set. 'Ihe valve |00 enables the cylinder 34 to besupplied with oil under pressure to cause air shutter 22 to be movedinto its low iiring rate position. The transition from high to low oilpressure does not interrupt the ow to nozzle 8.

The operation of the burner shown in Figs. 8 and 9, is the same as thatdescribed except that the air is introduced into the combustion chamber|45 by way of a large number of perforations |48 and |49 in theperipheral wall |46 and inner end wall |41, respectively. The air is fedthrough these walls in jets which are directed radially of thecombustion chamber from a large number of angular positions closelyspaced all around the entire circular extent of the spray and alsoclosely spaced along the length of the spray. 'Ihe jets through theperipheral wall |46 are at right angles to the axis of the spray whilethose through the end wall |4'Ivare at an acute angle to such axis andhave a component acting in a forwardly direction along the spray.

In the case of the Fig. 3 arrangement, the air is introduced through theperipheral wall 2 of the combustion chamber in whirling streams whichsurround the spray and to a considerable extent keep it from impingingon the wall of the combustion chamber and in any event keep such' wallwithin reasonable temperature lmits.- In the Fig. 8 arrangement, theradial iets of air have a similar eilect. In each case, the eiort is torestrain the flame, as much as possible, from impinging on the walls `oithe combustion chamber and to keep such walls relatively cool. In eachcase also, there is a lcontrolled distribution of the air-along most ofthe length of the llame, which results in better carburetion than couldbe had by the ordinary method of blowing the air from the open mouth ofan air supply tube in a direction generally lengthwise along an oilspray produced by an atomizing nozzle located in such mouth.Particularly, where the nozzle is operated at a pressure much less thanits rated pressure, the ordinary method of feeding air more or lesslengthwise along the oil spray will not result in good carburetionbecause there is not emcient atomization of the oil and a full spray isnot produced. It is necessary to compensate for the ineicientatomization of the oil'and this can be done with either of thecombustion chambers shown. The llame is ted with air by Jets or streamsentering through the peripheral wall of the combustion chamber andproviding a well distributed feed of air along a substantial length ofthe llame within the chamber. Except for the described distribution ofair to the combustion chamber, etlicient combustion could not be hadwhen the nozzle is operated at much less than its rated pressure.

Assume as one speciiic example that the nozzleusedisratedtoproduceaiiowotatomized oil at the rate of one gallon perhour when operated at a pressure of 100 pounds. By the use of acombustion chamber of the general type described and the special airfeed through the walls of such chamber, the nozzle can be operated atone half ofits rated pressur .orpoundatosecurea half gallon range l2 lowring rate of about .'I gallon per hour. Then by increasing the oilpressure to say 150 pounds,

a high rate of ilow of about 1.2 gallons per hourV can be produced.There is, it will be seen, a good range in theiiring rates availablefrom a. standard one-gallon per hour nozzle. The example describedisconservative. It is possible to reduce the cil pressure to about 25pounds mr square inch and secure a low firing rate of onehalf gallon perhour from this one particular size 01' nozzle. This will increase thefiring range to .7 gallon. Generally the half-gallon range in firingrates suiiices for a nozzle of the one gallon per hour ji-ating. Thisparticular size o1' nozzle is the smallest that is ordinarily thoughtfeasible to use except under special conditions. It does not.y when usedin the conventional way, enable a low enough rate of oil ow for the lowiiring rate. It might perhaps be operated in the conventionalway at apressure slightly under pounds per square inch but the diil'erence inrate oi flow produced would not be appreciable.

For 'any given rangeof ilring ratesdesired, the range of oil pressuresnecessary to produce the change in such rates from a nozzle of any givencharacteristics, increases rapidly as the low tiring 4rate is increased.The ilow from an oriilce of any given size varies approximately inproportion tothe square vroot oi the pressures used. In the examplegiven, one-half gallon range is had from a nozzle rated to produce aiiow of one gallon per hour when operated at 100 pounds, by varying thepressure from 50 to 150 pounds per square inch-a pressure range of 100pounds per square inch. It was shown that a pressure range of 225 poundspersquare inch is necessary to get the same range in iiring rates if thelowtiring rate is o ne gallon per hour. If the low ring rate islo'weredto one half gallon per hour by using oil pressure or about 25 pounds persquare inch, the high ring rate can be one gallon per hour and the highpressure 100 pounds per square inch. Here, the range in oil pressures isonly 'i5 pounds per square inch. This lastnamed example probablyrepresents the lowest limit feasible. Itillustrates theA point that thelower the low ring rate, the less is the increase in pressure necessaryto get the high ring rate with any given range in iiring rates. Startingat 25 pounds per square inch pressure, the prespounds per square inchfor the in ilring rates; if the low pressure is 0 poundsv per squareinch, the pressure range will be 100-pounds per square inch, and if thelow pressure is 100. pounds per square inch, the pressure range is Vpounds per square inch for the s'ame firing range.

The invention enables an ilring rate, lower than can be normally hadwith a pressure atomizin'g nozzle in a gun type burner; it provides forthe change in ring rates by changing the pressure of the oil fed to theatomizing= nozzle and with a smaller spread in oil pressure than couldbe had from a pressure atomizing nozzle in a conventional gun type oilburner it'l keeps the maximum oil pressure within the limits of thecapacity of the oil pumps usually used in gun type oil burners; and itprovides, within the burner structure, a combustion chamber in which thegreater part of the combustion occurs, so that the wide spread in tiringbe had because the burner operation win not be limited by limitations ofsize of the s paratus for regulating the pressure of the oil supto saidconduit and nozzle to set such apparatus to predetermirie a pressure forthe oil supply to the nozzle substantially lower than the pressure forwhich its atomizing efficiently is predetermined, another valve-settingmeans interlocked with said first valve-setting means to alternately andonly alternately set such apparatus to predetermine a pressure for theoil supply to the nozzle substantially higher than the pressure forwhich its atomizing eiciency is predetermined, whereby the regulatingapparatus may be set for a firing rate lower or higher than saidiirst-named rate, an air supplyjan, an air tube of the gun-burner typeconnected to receive the air from the fan, an adjustable shutter for thefan to determine the rate at which air is supplied to said tube, asecond tube forming within it a combustion chamber and mounted in spacedcoaxial relation in the air tube forming between it and the air tube ajacket, a closure for the forward end of the jacket, the rear end beingopen to receive air from the fan, the rear end of the second plied bythe pump valve-setting means tube being partially closed and its frontend be ing open, the peripheral wall of the second tube having openingstherein for air to enter the coinbustion chamber from said jacket, saidnozzle being positioned in the rear end of the combustion chamber toemit oil forwardly toward its open front end to mix with air suppliedthrough the openings in the peripheral wall of the combustion chamber tocompensate for lowered eiliciency of atomization at the low iiring rate,a power operated device to move said shutter to one predeterminedposition to secure a relatively low rate of air flow and provide for aneiiicient airoil burning ratio for the low pressure setting of saidvalve regulating meansv and to another predetermined position to securea relatively high rate of air flow and provide for an efcient airoilburning ratio for the high oil pressure supply setting of said valveregulating means, and means interlocking said power device and saidpressure-regulating valvev apparatus to cause the shutter to be moved tosaid low rate or high rate position whensaid apparatus is respectivelyset for said low or high pressur 2. In an oil pressure atomizing burnerof the kind having an oil pressure atomizing nozzle, adjacent ignitionmeans, power mechanism to pump oil through the nozzle at a predeterminedconstant pressure according toA adjustment, a power fan to supply air ata predetermined constant rate according to adjustment, and an air tubeto direct air from its supply to meet the oil from its supply, thecombination of a tube spaced within the air tube and forming acombustion chamber, the nozzle and the ignition means being positionedat the rear portion of the combustion chamber to project atomized oillengthwise thereof, the forward end of the combustion chamber being openadjacent the forward end of the airvtube' and the space between saidtubes being closed of! at such forward end while its rear end is open toreceive air from the fan. shielding walls at the rear end oi' thecombustion, chamber to direct air\ from the fan for the most part to thespace between the tubes, and thence tangentlally through slottedopenings into the combustion chamber to meet the atomized oil along itslength in the form of a forwardly pressed whirling layer of theair-supply, adjustable pressure-regulating valve means for regulatingthe pressure of the oil supplied by the pump to said nozzle and thus thepressure at which oil is atomized, quick-acting power-operated means forchanging the adjustment of said valve means from one constantpredetermined rate to a substantially different one to change the oilburning rate of the burner from a relatively low rate to a relativelyhigh rate of substantial dierence due solely to the change in the amountof the atomizing pressure, and interlocked operating means between thepressure changing means and said air supply shutter to cause the latterto take a position to correspond with a change in atomizing pressure.

3. In an voil pressure atomizing burner of the gun type for domesticheating and of the kind having a motor-operated air-supply fan andoilsupply pump, an air tube connected to receive air from the fan, anatomizing nozzle, a conduit connecting the pump and nozzle, and ignitionmeans adjacent the nozzle for igniting the air and oil mixture, such asis generally adapted for operation at a single firing rate due to apredetermined size of nozzle which is rated lfor a predeterminedpressure for atomizing oil to give -such iiring rate, the combination ofadditional elements for and some rearrangements of the elements of sucha burner to convert it to a dual rate burner, comprising an automaticpressureregulating-valve mechanism for regulating the pressure of oilsupplied by the oil pump to said atomizing nozzle, such mechanism havinga hand-operable precision-adjustable device to predetermine a relativelow pressure operation for such regulating valve mechanism and a secondand similar precision device to predetermine a relative high pressureoperation for such valve mechanism, quick-acting power means to set suchmechanism in condition to automatically regulate the pressure of the oilas pumped for the low or the high pressure delivery to the nozzle, ashutter mechanism for the fan to determine a high or low rate of airsupply for the burner operation, the latter mechanism also having twohand-operable precision-adjustable devices, one for its low air rate andone for its high air rate, said shutter mechanism having means to set itfor one or the other of said air rates, such lastnamed means beingactuated by and interlocked with the aforesaid quick-acting powermeans-so thatthe shutter is set for the high or low rate of air supplywhen said mechanism is respectively set for high or low pressur andmeans to compensate for the lack of atomizing efliciency of said ratednozzle when operated at a lower oil pressure than the nozzle rating,said last-named means comprising a combustion-chamber-forming inner tubebuilt within said air tube in spaced and coaxial relation, saidv nozzleand said adjacent ignition means being positioned at the rear end ofsuch combustion chamber, said inner tube forming the combustion chamberhaving air feed openings adapted to feedy the air to the oil in awhirling sheet extending around the com- REFERENCES CITED The followingreferences are 111e of this patent:

of record in the Number 18 UNITED STATES PATENTS Name Date Powers May27, 1924 Scheifele Dec. 25, 1934 Senmnger Apr. 9, 1946 Logan Nov. 12,1946 Logan et al Mar. 15, 1949

